Here is a repost of an article sent to me by Aaron Silber.
Can’t get much of a better source than Mark. He wrote an article on pushing the limits of Windows, in the article he goes through many things including memory and this very heated topic. Finally there is an easy way to figure out exactly how to set the pagefile.
In a nutshell, the recipe is as follows: start up all of your applications that you think will be run (or wait a decent amount of time until the system has had good usage), then launch Process Explorer and go to the view menu and select System Info look at the Commit Charge | Peak, set the paging file to be this number minus the amount of ram in your system. That’s it!
Have a look at the whole article, well worth the read here: http://blogs.technet.com/markrussinovich/archive/2008/11/17/3155406.aspx